Time of flight ranging systems find use in level measurements applications, and are commonly referred to as level measurement systems. Level measurement systems determine the distance to a reflective surface (i.e. reflector) by measuring how long after transmission energy, an echo is received. Such systems may utilize ultrasonic pulses, pulse radar signals, or other microwave energy signals.
Pulse radar and microwave-based level measurement systems are typically preferred in applications where the atmosphere in the container or vessel is subject to large temperature changes, high humidity, dust and other types of conditions which can affect propagation. The high frequency nature of such systems make them less susceptible to signal degradation due to the effects of humidity, dust and the like in the operating environment.
Level measurement devices may also utilize a FMCW radar transmitter system. A FMCW radar level transmitter system transmits a continuous signal during the measurement process. The frequency of the signal increases or decreases linearly with time so that when the signal has travelled to the reflective surface and back, the received signal is at a different frequency to the transmitted signal. The frequency difference is proportional to the time delay and to the rate at which the transmitted frequency was changing. To determine the distance that the reflector is away from the radar transmitter, it is necessary to analyze the relative change of the received signal with respect to the transmitted signal as will be appreciated by those skilled in the art.
Pulse radar, microwave and FMCW radar based level measurement systems include electronics and circuitry which operate under high and/or very high frequencies as described above. Electronic circuitry operating at high frequencies requires shielding to eliminate or minimize the unwanted effects of high frequency signals or signal processing, such as EMI (electromagnetic interference). Shielding techniques or mechanisms are a typical requirement in the design of high frequency circuitry. Accordingly, there remains a need for improvements in high frequency design components or elements for radar-based level measurement systems.